Sanders, who lost out to Hilary Clinton in the battle to become the Democratic presidential candidate last year, said he was "delighted" for Corbyn. He added that the vote sent an important socialist message.

"People in the UK, the US and elsewhere want governments that represent all the people, not just the 1%. I congratulate Jeremy Corbyn for running a very positive and effective campaign."

Corbyn is on course to secure 261 seats, up from 232 in 2015, a result that few expected when Prime Minister Theresa May called an election in April. May, who was predicted to win by a landslide majority, is expected to secure 319 seats, not enough for a Parliamentary majority. This is down on 331 on 2015.